So, I'm sure I am guilty of being the reason why this started happening... I have a P0300 code I haven't solve for over a year (unplugged the MAP sensor and it runs fine), and I drive this thing like a jockey on race day... Or at least I use to.

It started a couple weeks ago. I can hear it more like a clack clack clack sound. I can hear it between shifts (manual trans) and when in gear at around 2000 rpm.

If I am at 2000 rpm and push the gas peddle down it disappears and if I let off the gas it disappears too. I can hear it when I'm under the hood and the car has been driven for a while (up to temp). It is definitely not the injectors... I can hear them too... and they are a different sound.

I put my "stethoscope" up to the valve cover and I could hear it clear as day. Also, it is consistent with engine speed. Oil level is spot on.

My question is if this is going to cost a lot to fix? and what component(s) is it? Thanks in advance.